Hydrocracking nitrogen-contaminated hydrocarbon charge stocks



Jan. 16, 1968 c. H. WATKiNS 3,354,131

HYDHOCRACKING NITROGEN-CONTAMINATED HYDROCARBON CHARGE STOCKS Filed Dec. 9, 1965 2 Sheets-Sheet 1 Figure 120 \OAO/Z 5 a0 '6 D; E a- 60 S a Q) n:

4 0 IOJ/O Percent Alumina in Alum/ha Silica //V VEN TOR" 0/7 ar/es H. Watkins A TTOR/VEYS Jan. 16, 1968 c. H. WATKINS HYDROCRACKING NITROGENCONTAMINATED HYDROCARBON CHARGE STOCKS 2 Sheets-Sheet 2 Filed Dec. 9. 1965 Figure 2 2 V\ m fi o Tm Mi Ill 0 0 0 0 0 w m 6 5 4 3 2 mw .5 QSQEQQ 393m @233;

Percent A lum/na in A lumina- Silica IV VE/V TOR: Char/es H. Waf/r/ns A TTO/PNEYS United States Patent Ofilice 3,354,131 Patented Jan. 16, 1968 3,364,131 HYDROCRACKING NITROGEN-CONTAMINATED HYDROCARBON CHARGE STOCKS Charles H. Watkins, Arlington Heights, Ill., assignor to Universal Oil Products Company, Des Plaines, 11]., a corporation of Delaware COHtlIllllfiOll-lH-Pfllt of application Ser. No. 390,834, Aug. 20, 1964, which is a continuation-in-part of application Ser. No. 248,812, Dec. 31, 1962, which is a continuationm-part of application Ser. No. 18,743, Mar. 30, 1960. This application Dec. 9, 1965, Ser. No. 512,705

5 Claims. (Cl. 208-59) The present application is a continuation-in-part of my copending application, Ser. No. 390,834, filed Aug. 20, 1964, now abandoned, in turn being a continuation-inpart of my copending application, Ser. No. 248,812, filed I )ec. 31, 1962, and now abandoned, which is a continuation-in-part of my copending application Ser. No. 18,743, filed Mar. 30, 1960, and now abandoned, all the teachings of which applications are incorporated herein by specific reference thereto.

The invention encompassed by the present application relates to the multiple-stage processing of heavy hydrocarbonaceous material to convert the same into lowerboiling liquid hydrocarbon products. More specifically, the present invention is directed toward an improvement in a multiple-reaction zone process for catalytically converting hydrocarbons boiling at temperatures above the gasoline boiling range, and severely contaminated by the presence of exceedingly large quantities of nitrogenous compounds, into high yields of various hydrocarbon fractions boiling within the normal gasoline boiling range.

Hydrocracking, Which is also commonly referred to as destructive hydrogenation, may be designated as cracking under hydrogenation conditions such that the lowerboiling products of the cracking reactions are substantially more saturated than when hydrogen, or material supplying the same, is not present. Hydrocracking processes are most commonly employed for the conversion of coals, tars and various heavy residual oils for the purpose of producing substantial yields of lower-boiling saturated products. Although many of these hydrocracking reactions, or destructive hydrogenation processes, may be, and are, conducted on a thermal basis, the preferred processing technique involves the utilization of a catalytic composite possessing a high degree of hydrocracking activity. In virtually all hydrocracking processes, whether thermal or catalytic, controlled or selective cracking is desirable from the standpoint of producing an increased yield of liquid product having improved, advantageous physical and/or chemical characteristics, and to assure edective catalytic action over an extended period of time. Controlled, selective hydrocracking is of particular importance when processing hydrocarbons and mixtures of hydrocarbons boiling at temperatures above the middledistillate boiling range; that is, hydrocarbons and mixtures of hydrocarbons, as well as various hydrocarbon fractions and distillates, having a boiling range indicating an initial boiling point of from about 550 F. to about 700 F. and an end boiling point which may be as high as 1000 F., or more. Selective hydrocracking of such hydrocarbon fractions results in greater yields of hydrocarbons boiling within and below the middle-distillate boiling range; that is, hydrocarbons and hydrocarbon fractions having an initial boiling point of from about 350 F. to about 450 F. and an end boiling point of from about 550 F. to about 700 F. In addition, selective hydrocracking of such heavier hydrocarbon fractions results in a substantially increased yield of gasoline boiling range hydrocarbons; that is, those normally liquid hydrocarbons and hydrocarbon fractions having an end boiling point of from about 350 F. to about 450 F. Economically successful hydrocracking processes must be selective in order to avoid the decomposition of normally liquid hydrocarbons substantially or completely into normally gaseous hydrocarbons.

Investigations into the process of hydrocracking heavier hydrocarbons have indicated that the presence of nitrogen-containing compounds within the hydrocracking feedstock, such as naturally-occurring, organic nitrogenous compounds, examples of which include pyrroles, amines, indols, and other classifications of organic nitrogen-containing compounds, results in the relatively rapid deactivation of the catalytically active metallic components serving as the hydrogenation and/ or hydrocracking agent, as well as the solid carrier material which acts as the acidic hydrocracking component of a great variety of hydrocracking catalysts. Such deactivation appears to result from the reaction of the nitrogen-containing compounds with the various catalytic components, the extent of such deactivation increasing as the process continues and as the nitrogen-containing feedstock continues to contaminate the catalyst through contact therewith. It is believed that the formation of a nitrogen-containing complex, with the catalytically active metallic components, whereby the active surfaces and centers of the catalyst, normally available to the hydrocarbon charge stock, are eflectively shielded therefrom, is the predominating effect having the greatest influence in regard to catalyst deactivation.

In order to etfect an acceptable, economically feasible hydrocracking process, when processing nitrogen-containing feedstocks, the prior art proposes various multiplestage reaction systems. In these processes, the nitrogencontaining charge stock is generally initially processed in a reaction zone under conditions of operation conducive to hydrorefining reactions resulting in the destructive removal of the nitrogenous compounds and other contaminating influences including sulfurous compounds into hydrocarbons, ammonia and hydrogen sulfide, as well as the saturation of monoand di-olefinic hydrocarbons. The liquid phase portion of the product efiluent is then usually subjected to catalytic hydrocracking in one or more subsequent reaction zones 'for the purpose of converting the substantially nitrogen-free hydrocarbons into lower-boiling hydrocarbon products. The primary ob e ct of the present invention is to provide an improvement n such a multiple reaction zone process for the catalytic conversion of hydrocarbonaceous material, contaimng nitrogenous compounds, into lower-boiling hydrocarbon products. As hereinafter indicated by speclfic example, the improvement resides in the chemical character of the catalytic composites which may be utilized 1n the reaction zones. The use of the improvement of the present invention results in a process which produces substantially greater yields of hydrocarbons boiling within the gasoline and middle-distillate boiling ranges, Without the usual attendant saturation of aromatic compounds, accompanied by the uncontrolled cracking of low molecular weight hydrocarbons. A related Ob ect 1s, therefore, to provide a process which can function econom cally for an extended period of time as a result of the increased efiiciency arising through the use of the improved catalytic composites.

Therefore, in a broad embodiment, the present invention relates to an improvement in a multiple-reaction zone process for catalytically converting hydrocarbonaceous material, containing nitrogenous compounds, into lowerboiling hydrocarbon products, which process comprises reacting said hydroearbonaceous material with hydrogen in a first reaction zone containing a catalytic composite, and further reacting at least a portion of the first reaction zone effluent with hydrogen, at cracking conditions and in contact with a hydrocracking catalyst disposed in a subsequent reaction zone, which improvement comprises effecting the reaction in said first reaction zone in contact with a catalytic composite of catalytically active metallic components and a refractory inorganic oxide carrier material comprising from about 60.0% to about 78.0% by weight of alumina, and effecting further reaction in said subsequent reaction zone with a catalytic composite of catalytically active metallic components and a refractory inorganic oxide carrier material Containing from about 12.0% to about 30.0% by weight of alumina.

A more limited embodiment of the present invention involves an improvement in a multiple-reaction zone process for the catalytic conversion of hydrocarbonaceous material containing nitrogenous compounds, into lowerboiling hydrocarbon products, which process comprises reacting said hydrocarbonaceous material with hydrogen in a first reaction Zone containing a catalytic composite, removing ammonia from the resultant first reaction zone efiluent, separating the eilluent into at least a first fraction having an end boiling point less than about 450 C., and reacting a portion of the remainder of said first reaction zone efiluent with hydrogen, at cracking conditions in contact with a hydrocracking catalyst disposed within a subsequent reaction zone, which improvement comprises effecting the reaction in said first reaction zone in contact with a catalytic composite of from about 4.0% to about 45.0% by weight of molybdenum, from about 1.0% to a about 6.0% by weight of nickel and a carrier material containing silica and from about 60.0% to about 78.0% by weight of alumina, and effecting further reaction in said subsequent reaction zone with a catalytic composite of from about 0.1% to about 2.0% by Weight of palladium and a carrier material containing silica and from about 12.0% to about 30.0% by weight of alumina.

From the foregoing embodiments, it will be noted that the improvement in multiple stage hydrocracking processes, encompassed by the present invention, is specifically directed toward the composition of the catalytic composite disposed within the various reaction zones. In this regard, the term, metallic component, or catalytically active metallic component, is intended 'to encompass those components of the catalytic composite which are employed for their hydrocracking activity, their hydrogenation activity, or for their propensity for effecting the destructive removal of nitrogenous compounds, sulfurous compounds, as the case may be. These catalytically active metallic components are selected from the metals and compounds of Groups VI-B and VH1 of the Periodic Table of the Elements, Fischer Scientific Company, 1953. In this manner, the metallic components are distinguished from those components which are employed as the solid support, or carrier material, and which are generally referred to as refractory inorganic oxides. The metallic component of the catalyst of the present invention may comprise mixtures of two or more of the metals and compounds of Groups VI-B and VIII of the Periodic Table. Thus, the catalyst'may comprise chromium, molybdenum, tungsten, iron, cobalt, nickel, palladium, platinum, ruthenium, rodium, osmium, iridium, nickel-molybdenum, nickel-chromium, molybdenum-platinum, cobalt-nickelmolybdenum, molybdenum-palladium, chromium-platinum, chromium-palladium, molybdenum-nickel-pallad ium, etc. However, since the improvement of the present invention is applicable to multiple-reaction zone hydrocracking processes, in each of which reaction zones the catalytic composite is intended to serve a different function, each reaction zone will make use of a catalytic composite different, in most applications of the present invention, from the catalyst employed in other reaction zones. These different catalytic composites will hereinafter be described with reference to the particular reaction zonein which employed, and in'regard to the particular function to be served. Heretofore, regardless of the particular catalytically active metallic components employed, or the state in which they exist within the composite, they were generally combined with a suitable, solid carrier material which may have been either naturallyoccurring or synthetically-prepared. Thus, the carrier material can be naturally-occurring aluminum silicates, various alumina-containing clays, sands, earths and the like, while synthetically-prepared catalytic components have generally included one or more refractory inorganic oxides selected from a group including zirconia, magnesia, thoria, boria, silica, alumina, titania, strontia, hafnia, etc.

The applicability of the improvement encompassed by the present invention, to a multiple-stage hydrocracking process, may be illustrated by assuming a process in which there are two reaction zones, the object being to produce a maximum quantity of gasoline boiling range hydrocarbons and middle-distillate boiling range hydrocarbons, from a highly contaminated charge stock having an initial boiling point of about 650 F. and an end boiling point of about 950 F. With such a charge stock, the first reaction zone is employed for the primary purpose of effecting the virtually complete removal of the nitrogenous compounds by converting the same into ammonia and normally liquid hydrocarbons, while simultaneously converting sulfurous compounds into hydrogen sulfide and liquid hydrocarbons. Generally speaking, the overall process is enhanced by virtue of the fact that some hydrogenation and hydrocracking of the higher-boiling components also takes place. Following the removal of the ammonia, hydrogen sulfide and minor quantities of light parafiinic hydrocarbons including methane, ethane and propane, the normally liquid product efiluent from this first reaction zone is generally subjected to separation to remove a lower-boiling gasoline fraction containing hydrocarbons boiling below a temperature of about 425 F. to about 450 F. The remainder of the normally liquid portion of the first reaction zone efiluent is then passed into a second reaction zone, the primary purpose of which is to effect a high degree of conversion into lower-boiling products. Heretofore, it was believed, and the prior art so indicates, that the propensity of a given catalytic composite for the destructive removal of nitrogenous compounds, was in direct proportion to the amount of alumina utilized in the carrier material. That is, as the percentage of alumina was increased, there wasexperienced an increase in the removal of nitrogenous compounds, or conversely a decrease in the quantity of residual nitrogen remaining in the normally liquid product. On the other hand, it was believed that the quantity or degree of hydrocracking was dependent upon and directly proportional to the amount of silica contained within the carrier material, or, by increasing the quantity of silica the conversion obtained under a given set of operating conditions was increased.

To the contrary, I have now found that the degree of nitrogen removal effected in the first reaction zone,

as a result of the various hydrorefining reactions, is not simply a matter of increasing the quantity of alumina, or decreasing the silica, in the catalytic composite disposed therein. Similarly, I have also found that the degree of conversion into lower boiling hydrocarbon prod-.

sequent hydrocracking reaction zones; This critical range.

of alumina, depending upon in which reaction zone the catalyst is employed, and whether primarily as a hydro-- refining catalyst, or as a hydrocracking catalyst, has not been recognized by the prior art in this field. Notwithstanding that multiple-stage processes. of this nature abound in the prior art, there has been no teaching of the fact that the catalytic composites must be prepared using a carrier material having a concentration of alumina in a particularly narrow range. Typical of such prior art multiple-stage processes are those set forth in US. Patent No. 3,008,895, issued to R. C. Hansford and US. Patent No. 3,072,560, issued to N. I. Paterson. These processes stress the use therein of hydrocracking catalysts containing significantly less alumina than the minimum amount herein set forth, or catalysts entirely void of alumina, i.e., silica-zerconia-titania. The catalysts for use in the hydrorefining, or dinitrogenation, portion of the process are either not highly acidic, containing much less silica, or entirely alumina, as contrasted to the present invention wherein the hydrorefining catalyst contains a significant quantity of silica. It is this type of prior art process to which the present invention affords a great improvement.

This criticality of alumina concentration within the carrier material, employed in the preparation of the various catalytic composites, is illustrated in accompanying FIGURE 1, relating to the catalyst employed primarily to effect the removal of nitrogen, as well as other hydrorefining reactions, and in FIGURE 2, relating to the catalyst employed for the purpose of converting hydrocarbons boiling above a temperature of about 650 F. into lower-boiling hydrocarbon products. The data utilized in formulating FIGURES 1 and 2 were obtained in accordance with the specific examples hereinafter set forth. Briefly, however, with reference to FTGURE 1, data points 1, 2, 3, 4, 5, 6, through which curve 7 is drawn, were obtained by processing a heavy vacuum gas oil containing total nitrogen in an amount of 1193 p.p.m., at constant operating conditions, varying only the composition of the carrier material employed in preparing the catalytic composites. As indicated, the carrier material was, in all instances, a composite of alumina and silica, and each carrier material, following the formation thereof, was impregnated with 1.2 grams of nickel and 10.0 grams of molybdenum per 100 cc. of the respective carrier material. Dotted line A, indicating a residual nitrogen concentration of 10.0 p.p.rn., intersects line 7 at points 8 and 9; a residual nitrogen concentration of 10.0 ppm. is generally considered to be the maximum which can be tolerated in a hydrocarbon fraction or distillate intended for use as the charge material to a hydrocracking reaction zone; thus, this amount is likely criteria to use for evaluation. Intersections 8 and 9 represent an alumina-silica carrier material containing 60.0% and 78.0% by weight of alumina, respectively. The criticality attached to this range of alumina concentration is readily ascertained by the character of the curve, in that an alumina concentration less than 60.0%, or more than 78.0% produces a catalytic composite which results in a liquid product efiluent containing more than 10.0 ppm. of residual nitrogen, which is, therefore, not Well-suited for subsequent processing in the hydrocracking reaction zone.

Similarly, with brief reference to FIGURE 2, data points 101, 102, 103, 104 and 105, through which curve 106 has been drawn, were obtained by processing a contaminant-free heavy hydrocarbon oil (having a boiling range of from about 700 F. to about 900 F.), under constant operating conditions. Dotted line B, intersecting curve 106 at points 101 and 167, is drawn to represent a constant conversion, to hydrocarbons boil-' ing below a temperature of 650 F., of 63.0% by volume, based upon the quantity of material charged to the reaction zone. Intersections 101 and 107 represent a carrier material of alumina and si ica in which the concentration of alumina is 12.0% and 30.0% by weight, respectively. The criticality of this range of alumina concentration is readily ascertained from the character of the curve 106. Catalysts which are prepared utilizing carrier materials containing less than about 12.0% by weight of alumina, or more than 30.0% by weight of alumina, do not result in conversions of a magnitude greater than 63.0% by volume of hydrocarbons boiling below a temperature of about 650 F.

The character of the curves in FIGURES 1 and 2 are unusual, and totally unexpected in view of the teachings of the prior art respecting the composition of the carrier material utilized in the preparation of catalytic composites suitable for utilization in multiple-reaction zone processes for hydrocracking nitrogen-contaminated charge stocks. It has clearly been shown that the degrees of nitrogen removal, and hydrocracking conversion of hydrocarbons, are not simply a matter of the random adjustment of the composition of the carrier material, but that unexpected benefits arise as a result of utilizing particular, narrow ranges of alumina in both the hydrorefining and hydrocracking catalytic composites.

Although the improved catalytic composites hereinbefore described are suitable for advantageous utilization in any multiple-reaction zone process for hydrocracking nitrogen-contaminated hydrocarbonaceous material, certain catalytically active metallic components and process ing techniques are particularly preferred. Thus, the contaminated hydrocarbon mixture is initially adm'med with hydrogen in an amount of about 1000 to about 8000 s.c.f./bb1. of liquid hydrocarbon charge, the mixture being raised to a desired operating temperature within the range of about 500 F. to about 1000 F., prior to contacting the catalytic composite disposed within the hydrorefining reaction zone. The hydrorefining reactions are effected under an imposed pressure of about pounds to about 3000 pounds per square inch, the hydrocarbon charge stock contacting the catalytic composite at a liquid hourly space velocity (defined as volumes of liquid charge per hour per volume of catalyst disposed within the reaction zone), within the range of from about 0.5 to about 10.0. In addition to the effective cleanup of the hydrocarbon charge stock, a significant degree of hydrocarbon conversion occurs whereby the heavier molecular weight hydrocarbons, boiling at a temperature of from about 700 F. to about 1000 F., and including the higher-boiling nitrogenous compounds, are converted, by highly selective cracking reactions into hydrocarbons boiling below about 700 F., from which the nitrogen is more readily removed. The conversion reactions are such that very little, if any, light, straight-chain paraflinic hydrocarbons are produced.

The catalyst disposed within the hydrorefining reaction zone serves a dual function; that is, the catalyst is nonsensitive to the presence of substantial quantities of both nitrogenous compounds and sulfurous compounds, while at the same time is capable of effecting the destructive removal thereof, and, as hereinabove set forth, the conversion of at least a portion of those hydrocarbons boiling at a temperature above about 700 F. A catalyst comprising comparatively large quantities of molybdenum, calculat d as the element, composited with the carrier material of silica and from about 60.0% to about 78.0% by weight of alumina, is very efhcient in carrying out the desired operation. A particularly preferred catalytic composite, for utilization in this reaction zone, comprises from about 4.0% to about 45.0% by weight of molybdenum. In addition to minor amounts of nickel, from about 0.2% to about 10.0% by weight, like quantities of cobalt and/ or iron may be employed in combination with the relatively large amounts of molybdenum. The composite, for utilization in this zone, may be manufactured in any suitable manner, a particularly advantageous method utilizes an impregnating technique after the carrier material has been prepared and formed into the desired size and/or shape.

The gaseous ammonia and hydrogen sulfide, resulting from the destructive removal of nitrogenous and sulfurous compounds, and light paraflinic hydrocarbons, are removed from the total efiiuent from the hydrorefining reaction zone in any suitable manner. For example, the effiuent may be admixedwith water, and thereafter subjected to separation such that the ammonia is absorbed in the water-phase. Hydrogen sulfide and light paraflinic hydrocarbons may be removed by introducing the effiuent into a low-temperature flash chamber, the normally liquid hydrocarbons from which are passed into a fractionating column for the purpose of removing those hydrocarbons boiling within the gasoline boiling range.

The remaining portion of the nitrogen-free efiiuent from the hydrorefining reaction zone, comprising those hydrocarbons boiling above a temperature of from about 425 F. to about 450 F., is combined with hydrogen in an amount of from about 1000 to about 6000 s.c.f./bbl. of liquid hydrocarbons, the mixture being raised to a temperature within the range of about 500 F. to about 950 F. Due to the characteristics of the charge stock to the hydrocracking reaction zones, the operating conditions within the same may be relatively mild. Therefore, the operating temperature at which the catalyst is maintained within the subsequent hydrocracking reaction zones, may be at least about 50 F. less than the temperature employed in the hydrorefining reaction zone. The reaction zone is maintained under an imposed pressure within the range of about 100 to about 3000 p.s.i.g., and the rate of hydrocarbon charge will be within the range of from about 1.0 to about 15.0 liquid hourly space velocity.

Catalytic composites which comprise at least one metallic component selected from Groups VI-B and VIII of the Periodic Table, and a composite of silica and from about 12.0% to about 30.0% by weight of alumina, constitute hydrocracking catalysts for use in the conversion of the nitrogen-free charge stock into lower boiling hydrocarbon products. The total quantity of catalytically active metallic components is within the range of from 0.1% to about 20.0% by weight of the total catalyst. The Group VI-B metal, such as chromium, molybdenum, or tungsten, is usually present within the range of from about 0.5% to about 10.0% by weight of the catalyst. The Group VIII metals, which may be divided into two sub-groups, are present in an amount of from 0.1% to about 10. by weight of the total catalyst. When an iron sub-group metal such as iron, cobalt, or nickel, is employed, it is present in an amount of from about 0.2% to about 10.0% by weight, while, if a noble metal such as platinum, palladium, iridium, etc., is employed, it is present within an amount within the range of from about 0.1% to about 5.0% by weight of the total catalyst. Suitable catalysts, for utilization within the hydrocracking reaction zone, include, but are not limited to the following: 6.0% by weight of nickel and 0.2% by weight of molybdenum; 6.0% by weight of nickel; 0.4% by weight of palladium; 6.0% by weight of nickel and 0.2% by weight of palladium; 6.0% by weight of nickel and 0.2% by Weight of platinum, etc.

The total efiiuent from the hydrocracking reaction zone is passed through a suitable high-pressure, low-temperature separation zone from which a hydrogen-rich gas stream is withdrawn and recycled to supply at least a portion of the hydrogen being admixed with the liquid hydrocarbon charge stock. The normally liquid hydrocarbons, containingsome light paraflinic hydrocarbons and butanes, are'combined with normally liquid hydrocarbons resulting from the separating means employed with respect to the hydrorefining reaction zone, to remove therefrom those hydrocarbons boilingwithin the gasoline boiling range. It is understood that the broad scope of the present invention is not to be unduly limited to a particular catalytically active metallic component or components, with respect to the catalyst disposed within the various reaction zones. Similarly, the improvement encompassed by the present invention is not intended to be limited to a particular flow pattern and/ or set of operating conditions within any of the reaction zones. The process, utilizing the improved catalytic composites of the present invention, may be effected in any suitable manner. a d may be either a batch or a continuous-type operation. When utilizing a continuous-type operation, which is the particularly preferred manner of effecting the present invention, the catalyst may be deposited as a fixed bed within the reaction zone, the hydrocarbons and hydrogen being continuously charged thereto and passing in either downward or upward flow through the catalyst bed.

As hereinbefore set forth, the process of the present invention is particularly directed to the processing'of hydrocarbons and mixtures of hydrocarbons boiling above the gasoline boiling range. However, it is most advantageously applied to petroleum-derived feedstocks, particularly those stocks commonly considered as being heavier than middle-distillate fractions. Such stocks include gas oil fractions, heavy vacuum gas oils, lubricating oils, and white oil stocks as well as the high-boiling bottoms recovered from various catalytic cracking operations. Therefore, although the charge stock to the present process may have an initial boiling point above about 650 F. and an end boiling point of about 1000 F. or higher, the process is not adversely affected by a charge stock having an initial boiling point as low as about 400 F. to about 450 F.

The following examples are given to further illustrate the process of the present invention and to indicate the benefits to be afforded through the utilization thereof. It is understood that the examples are given for the sole purpose of illustrating the means by which curves 7 and 106, in accompanying FIGURES 1 and 2 respectively, were obtained; they are not intended to limit the generally broad scope and spirit of the appended claims.

EXAMPLE I The data presented in this example is pertinent to accompanying FIGURE 1, and the latter should be referred to in conjunction with the following discussion. The bydrocarbon charge stock utilized in the test procedure for evaluating hydrorefining catalytic composites, in a heavy vacuum gas oil having a gravity, API at 60 F., of 21.8,

an initial boiling point of 495 F., a 50% volumetric distillation point of 766 F., and an end boiling point above about 900 F. The gas oil is contaminated by the presence of totalnitrogen in an amount of 1143 p.p.m., and contains 2.28% by weight of sulfur, calculated as if existing as the element. Catalyst portions in an amount of cc.

are employed in a reaction zone fabricated from schedule 40 stainless steel, and are maintained under an imposed pressure of 1500 p.s.i.g. The catalyst is maintained at a temperature of 750 F., and the charge stock is admixed with hydrogen in an amount of 7,500 s.c.f./bbl., the liquid hourly space velocity being 1.25. Following the removal of hydrogen sulfide and ammonia, in addition to any light of 1.24. The hydrosol mixtures were formed into spheri cal hydrogel particles in accordance with the oil-drop method as detailed in US. Patent No. 2,620,314, issued to James Hoekstra. The hydrogel particles were then dried at a temperature of about 200 F., and thereafter calcined at a temperature of about 1100 F. Each carrier material was subsequently impregnated with 1.2 grams of nickel and 10.0 grams of molybdenum per 100 cc., dried, cal-' cined and subjected to the activity test procedure hereinabove described. The following Table I indicates the catalyst designation (having reference to the datum points of accompanying FIGURE 1), the quantity of alumina in the carrier material, the residual nitrogen in the liquid product effluent, and the percentage conversion to hydrocarbons boiling below a temperature of 400 F.

TABLE I.EVALUATION FOR HYDROREFI'NiN'G ACTIVITY CatalystNo "'II23I4I5IG From the data presented in foregoing Table I, and With reference to accompanying FIGURE 1, it will be seen that the six catalysts, having increasing concentrations of alumina in the carrier material, the latter ranging from 25.0% to 88.0% by weight, did not produce normally liquid hydrocarbon products of decreasing residual nitrogen concentration. This is clearly brought out upon comparing the results obtained through the use of catalysts 3, 4, and 6, which resulted in a product efiluent containing 90, 2.0, 3.6 and,80 ppm. of nitrogen, respectively. These data were employed in preparing curve 7 of FIG- URE 1, which curve clearly illustrates the criticality attached to an alumina concentration within the range of about 60.0% to about 78.0% by weight, in order to produce a normally liquid product effluent containing less than about 10.0 ppm. of residual nitrogen. Another unusual, totally unexpected advantage of utilizing a carrier material containing alumina in the aforesaid range, resides in the quantity of hydrocracking effected, notwithstanding that the operating conditions are chosen primarily to promote hydrorefining reactions in order to effect nitrogen removal. It will be noted that catalysts 4 and 5, containing alumina in an amount of 63.0% and 75.0% by weight respectively, exhibited the greater degree of hydrocracking ot produce hydrocarbons boiling below 400 F. The additional economic advantages afforded through this particular result will be readily recognized by those possessing skill within the art of petroleum refining processes, and particularly those involving the decontamination of charge stocks intended for subsequent processing.

EXAMPLE II This example is presented for the purpose of illustrating the criticality attached to the concentration of alumina with respect to the catalyst employed for the purpose of effecting the hydrocracking of high boiling hydrocarbon charge stocks which have been previously subjected to hydrorefining reactions for the purpose of removing various contaminating influences including nitrogenous and sulfurous compounds. The charge stock was a heavy gas oil having a gravity, API at 60 F., of 28.6, an initial boiling point of 690 F. and an end boiling point of 875 F.; the gas oil contained less than 0.1 p.p.m. of nitrogen, and indicated nil upon analysis for sulfur.

Five catalysts were prepared from carrier materials of varying alumina concentration; although the ratio of alumina to silica varied, the carrier materials were made in the same manner. An alumina-silica hydrogel was coprecipitated from a mixture of hydrosols resulting from the commingling of aluminum sulfate and acidulated water glass, the coprecipitation being effected through the utilization of ammonium hydroxide. After being filtered and washed free of various salts, the hydrogel was dried at a temperature of about 200 F., formed into Az-inch by Aa-inch cylindrical pills, the latter being calcined at a temperature of about 1100 F. Each of the five carrier materials were impregnated with sufiicient chloropalladic acid to deposit 0.4% by weight of palladium. These catalysts, formed from carrier materials containing 12.0%, 25.0%, 37.0%, 46.0% and 63.0% by weight of alumina, the remainder of each being silica, were subjected to a hydrocracking relative activity test procedure utilizing the contaminant-free hydrocarbon mixture above described.

The activity test procedure is conducted -by processing the hydrocarbon fraction at 1500 p.s.i.g. and -a catalyst temperature of 600 F., in the presence of 3000 s.c.f./

10 bbl. of hydrogen. For each catalyst, three test periods are effected at liquid hourly space velocities which vary from 1.0 to 4.0. The normally liquid product effluent from each of the three test periods is subjected to distillation to determine the quantity of hydrocarbons boiling below a temperature of 650 F., and these three percentages are plotted against the space velocities employed to obtain the same. The relative activity is determined by the ratio of the liquid hourly space velocity required to produce a product effluent of which 60.0% by volume is distilled at a temperature of 650 F., and comparing this liquid hourly space velocity with that of a standard catalyst. With respect to a given test catalyst, a relative activity coefiicient greater than indicates a catalyst having a greater degree of hydrocracking activity than the standard reference catalyst, and in this manner, numerous test catalysts may be compared with each other. The following Table II shows the evaluation of hydrocracking activity with respect to the five catalysts under consideration; these catalysts are numbered to correspond with the datum points in accompanying FIGURE 2.

TABLE II.-EVALUATION OE HYDROCRACKING ACTIVITY Catalyst Number "I 101 i 102 103 I 104 i 105 Alumina Concentration"... 12 25 37 46 03 Relative Activity 108 147 53 31 21 Percent. Below 650 F 63 74 40 33 30 With reference to FIGURE 2, points 101, 102, 103, 104 and 105 represent the percent conversion of the highboiling charge stock into hydrocarbons boiling below 650 F., at a liquid hourly space velocity of 3.0. Obviously, a curve of similar character to curve 106 would be obtained if the correlation were made between the alumina concentration and the relative activity coefficients indicated in the foregoing Table II. Dotted line B," in FIGURE 2, represents a volume percent conversion at 650 F. of 63.0, and was chosen by virtue of the fact that tht catalyst containing the lowest quantity of alumina (catalyst 101) indicated this volume percent conversion at a space velocity of 3.0. From the character of the curve, the criticality attached to the quantity of alumina in the carrier material, from about 12.0% to about 25.0%, is readily ascertained.

The foregoing specification and examples clearly illustrate the improvement encompassed by the present invention and the benefits to be afforded a process for the production of lower-boiling hydrocarbon products from a nitrogen-containing, high-boiling hydrocarbon charge stock.

I claim as my invention:

1. In a multiple-reaction zone process for catalytically converting hydrocarbonaceous material, containing nitrogenous compounds, into lower boiling hydrocarbon products, which process comprises reacting said hydrocarbonaceous material with hydrogen in a first reaction zone containing a catalytic composite, and further reacting at least a portion of the first reaction zone eflluent with hydrogen, at cracking conditions and in contact with a hydrocracking catalyst disposed in a subsequent reaction zone the improvement which comprises effecting the reaction in said first reaction zone in contact with a catalytic composite of a catalytically active metallic component and a refractory inorganic oxide carrier material consisting essentially of silica and alumina containing from about 60.0% to [about 78.0% by weight of alumina, and effecting further reaction in said subsequent reaction zone in contact with a catalytic composite of a catalytically active metallic component and a refractory inorganic oxide carrier material containing from about 12.0% to about 30.0% by weight of alumina.

2. The improvement of claim 1 further characterized in that the catalyst disposed in said first reaction zone comprises at least about 4.0% by Weight of molybdenum,

1 1 and the catalyst disposed within said subsequent reaction zone comprises at least one metallic component selected from the metals of Groups VI-B and VIII of the Periodic Table and a carrier material containing silica and from about 12.0% to about 30.0% by weight of alumina.

3. The improvement of claim 1 further characterized in that the catalyst disposed within said first reaction zone is a composite of from about 4.0% to about 45.0% by Weight of molybdenum, 1.0% to about 6.0% by weight of nickel, and a carrier material containing silica and from about 60.0% to about 78.0% by weight of alumina, and the catalyst disposed within said subsequent reaction zone is a composite of a platinum-group metallic component and a carrier material containing silica and from about 12.0% to about 30.0% by weight of alumina.

4. The improvement of claim 3 further characterized in that the catalyst disposed within said subsequent reaction zone is a composite of from about 0.1% to about 2.0% by weight of palladium and a carrier material containing silica and from about 12.0% to about 30.0% by weight of alumina. A

5. The improvement of claim 1 further characterized in that the catalyst disposed Within said subsequent reaction zone is a composite of from about 0.2% to about 10.0% by weight of nickel, from about 0.1% to about 2.0% by weight of platinum, and a carrier material con taining silica and from about 12.0% to about 30.0% by weight of alumina.

References Cited UNITED STATES PATENTS 2,905,636 9/ 1959 Watkins et al 208254 3,008,895 11/1961 H-ansford et al. 20889 3,169,106 2/1965 Lefrancois et al. 208-111 ABRAHAM RIMENS, Primary Examiner.

DELBERT E. GANTZ, Examiner. 

1. IN A MULTIPLE-REACTION ZONE PROCESS FOR CATALYTICALLY CONVERTING HYDROCARBONACEOUS MATERIAL, CONTAINING NITROGENOUS COMPOUNDS, INTO LOWER BOILING HYDROCARBON PRODUCTS, WHICH PROCESS COMPRISES REACTING SAID HYDROCARBONACEOUS MATERIAL WITH HYDROGEN IN A FIRST REACTION ZONE CONTAINING A CATALYTIC COMPOSITE, AND FURTHER REACTING AT LEAST A PORTION OF THE FIRST REACTION ZONE EFFLUENT WITH HYDROGEN, AT CRACKING CONDITIONS AND IN CONTACT WITH A HYDROCRACKING CATALYST DISPOSED IN A SUBSEQUENT REACTION ZONE THE IMPROVEMENT WHICH COMPRISES EFFECTING THE REACTION IN SAID FIRST REACTION ZONE IN CONTACT WITH A CATALYTIC COMPOSITE OF A CATALYTICALLY ACTIVE METALLIC COMPONENT AND A REFRACTORY INORGANIC OXIDE CARRIER MATERIAL CONSISTING ESSENTIALLY OF SILICA AND ALUMINA CONTAINING FROM ABOUT 60.0% TO ABOUT 78.0% BY WEIGHT OF ALUMINA, AND EFFECTING FURTHER REACTION IN SAID SUBSEQUENT REACTION ZONE IN CONTACT WITH A CATALYTIC COMPOSITE OF A CATALYTICALLY ACTIVE METALLIC COMPONENT AND A REFRACTORY INORGANIC OXIDE CARRIER MATERIAL CONTAINING FROM ABOUT 12.0% TO ABOUT 30.0% BY WEIGHT OF ALUMINA. 